The present application relates to pen recorders and more particularly to accessories for use in conjunction with the pen and ink supply of a capillary tube type pen recorder.
A recorder such as wherein the present invention makes a useful accessory is shown in U.S. Pat. No. 3,906,513 to Siegelman et al. which is assigned to the assignee of the present invention. In such apparatus, an electrically operated pen motor drives a pen arm to move a metallic pen tip, comprising a capillary tube, transversely back and forth across a moving chart or recorder paper. The capillary tube pen having the pen tip at one end in contact with the moving chart paper has a capillary tubing connected thereto at the other end which in turn is connected to a supply of ink in an ink chamber. The tubing connecting the metallic pen capillary tube and the ink chamber is typically of polyethylene or polyvinyl chloride. Such recording systems are prone to a number of problems. One is splattering of the ink from the pen tip as the pen tip rapidly changes direction at the extremes of its traverse. Another is skipping caused by rapid movement of the pen tip over the recording paper. In an effort to solve these problems in a system wherein the ink must travel from the ink chamber through a considerable distance of capillary tubing before reaching the tip of the pen, various inks and ink supplying systems such as that described in Siegelman et al. are employed. The various inks and ink supply systems suggested in the art typically solve their particular problem when the system is actively operating. That is, as long as the chart paper is moving and causing ink to move through a well primed capillary tube system from the ink chamber through the capillary tubing to the pen tip, the whole operation continues smoothly.
Once the instrument is turned off for any period of time, however, additional problems present themselves. First, there is the tendency of the system to lose its prime. That is, the ink drains from the capillary tube, from the pen tip, back into the ink chamber, or evaporates through the walls of the tubing, or any combination thereof. As a result, when the instrument is once again started, the pen no longer writes until such time as the continuity of ink between the ink in the supply chamber and the pen tip is re-established. The second problem is the drying of the ink itself within the fine interior capillary passage of the metallic pen portion of the system. Once the ink has dried therein, it is often quite difficult to remove or dissolve the dried ink to restore proper operation to the system. Some prior art solutions to such problems are shown in the following patents:
U.s. pat. No. 2,308,710--E. P. Nichols PA0 U.s. pat. No. 2,977,180--W. J. Zenner PA0 U.s. pat. No. 3,039,438--J. T. L. Brown PA0 U.s. pat. No. 3,046,556--S. P. Summers, Jr., et al.
The solutions represented by these patents run from the simple to the quite complex. Heretofore, some of the simplest solutions have proved to be the best. One of the most common, still used, is the insertion of a rubber dam under the pen tip during periods of nonactivity. That is, the pen arm is merely lifted off the chart paper, a strip of rubber placed under the pen position and the pen arm lowered back down where the pen tip is in contact with the rubber instead of the paper. In so doing, the ink is not drawn from the pen tip by the rubber as it is by the capillary action of the fibers of the paper.
Another prior art device which has found some acceptance is shown in FIG. 1. In this device, a rubber bulb 10 having a hole 12, such as employed in perfume atomizers and the like, has a hollow rubber adapter 14 fitted thereto. Adapter 14 has a hole 16 communicating between the exterior and the interior thereof wherein a pen tip indicated as 18 can be inserted. In such a device, the pen tip can be inserted, and the bulb 10 squeezed with the user's thumb placed over the hole 12 to cause pressure to be exerted into pen tip 18. It can also be used to draw a vacuum to prime the pen 18 by depressing bulb 10 completely before inserting the tip of pen 18 into hole 16 and thereafter releasing the pressure while maintaining the user's thumb over hole 12 so that a vacuum is drawn in pen 18. While somewhat useful, the device pictured in FIG. 1 is limited in its accomplishments. It is also quite messy.
It is also possible to clean out the tubing connecting the pen with the ink supply by removing the pen, inserting a solvent-filled syringe into the tubing, and applying force to the syringe to force solvent through the tubing. Such a procedure can also be messy to say the least.
Wherefore, it is the object of the present invention to provide an accessory apparatus for use in conjunction with capillary tube ink writing systems which will allow an operator to prime the pen, clean the pen and connecting tubing, and leave the pen in periods of nonuse in a condition which will not require excessive effort to re-establish the writing condition.